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The P.W.S.26 was a basic and intermediate training aircraft that was produced in significant numbers in the late 1930s for the Polish air force, and that was the last member of a family descended from the P.W.S.12
Work on the P.W.S.12 began in 1927, as a biplane version of the parasol wing P.W.S.11 trainer. In 1931 the Polish Department of Aeronautics ordered twenty P.W.S.12s, but later in the year the order was changed to one for twenty P.W.S.14s, a modified version of the aircraft with a welded steel tube fuselage. However the changes in the orders and the failure of other P.W.S designs meant that the company went bankrupt in 1932, and was taken over by the Polish Government. In 1933 production switched to the P.W.S.16, which had a cleaner fuselage. This was followed by the P.W.S.16bis, which replaced the Townend ring of the earlier machine with a long-chord NACA cowling and had a new fuel system that allowed for long periods of inverted flight.
Although only twenty of the P.W.S.16bis were ordered, it impressed the Department of Aeronautics enough for it to order the development of a version that could carry guns and be used for dive bombing, which was to be used as the second main training aircraft of the Polish Air Force. Students would learn to fly on the RWD 8 primary trainer, then move to the new P.W.S.26 for basic and intermediate training, before then moving on to combat training with older combat aircraft.
The P.W.S.26 was almost identical to the P.W.S16bis. It was a staggered wing biplane, with ailerons on the upper wing. It was powered by a 220hp Polish Skoda Works licence built version of the Wright J.5 Whirlwind engine, contained in a NACA cowling. The only significant changes introduced on the P.W.S.26 were a new streamlined undercarriage, the ability to carry arms, and that it was stressed for dive bombing.
The P.W.S.26 was ordered straight into large scale production, without the need for a prototype, and the first flew late in 1936. By November 1938 239 P.W.S.26s were in service, with 188 with training units and 51 in reserve. A total of 250 had been built by the time production ended late in 1938.
Although the P.W.S.26 wasn’t a combat aircraft, some were used as liaison and reconnaissance types during the German invasion. Many were then captured and some were later used by the Luftwaffe. 28 were then sold to Romania. The Soviets also captured a significant number in Eastern Poland, and these may have seen some use.
P.W.S.27
The P.W.S.27 was the first of two variants of the P.W.S.26 that only reached the design stage. Both variants were given new wings with an elliptical plan. The upper wing was shaped almost like a boomerang, so that the trailing edge at the centre was in front of the pilot’s cockpit, while the lower wing had a straight trailing edge and partly curved leading edge. The aim was to make it easier to parachute out of the forward seat. The P.W.S.27 kept the 220hp engine of the P.W.S.26.
P.W.S.28
The P.W.S.28 was similar to the P.W.S.27, but was modified it to use 300hp engines.
Engine: Polish Skoda Works (Wright) J.5 Whirlwind nine-cylinder radial air-cooled engine
Power: 220hp
Crew: 2
Span: 29ft 6.75in
Length: 23ft 0.75in
Height: 9ft
Empty Weight: 1,874lb
Loaded Weight: 2,469lb
Maximum Speed: 134.8mph
Cruising Speed: 111.8mph
Climb rate: 3min 45sec to 3,280ft
Ceiling: 15,157ft
Range: 286 miles
Guns: Fixed fuselage mounted 7.7mm machine gun
Bomb load: One 26.5lb practice bomb under each wing